A conventional turf mowing machine includes one or more turf mowing units, or cutting units, which are either of the reel or rotary type. A reel cutting unit typically includes a frame carrying a horizontal bed knife and a horizontally rotating cutting reel which work in conjunction to shear the grass. A rotary cutting unit, on the other hand, includes a substantially planar deck under which is rotationally mounted one or more cutting blades for cutting the grass by impact. Each blade is driven by a pulley or hydraulic motor and the rotational axis of each blade-driving device is vertical. Reel cutting units are normally used when high precision cutting is in order. Rotary units are employed where greater cutting capacity is required and there is less need for precision. Although the present invention could be applied to any type of harvesting device cutting unit, for the sake of brevity the following discussion will focus on turf mowing apparatus having rotary cutting units.
Most of the moving parts of a rotary cutting unit, with the exception of the cutting blades themselves, are mounted on the top surface of the substantially planar deck, in an attempt to isolate the belts, pulleys, hydraulic motors, etc. from the dirt, grass clippings, and debris which normally accompany grass mowing. A deck cover, mounted horizontally to the deck, is often used to enclose the moving parts atop the deck for the sake of safety and to further eliminate fouling of the moving parts by debris. The present invention is primarily directed toward such a deck cover, and is also pertains to unique means for securing the deck cover to the deck.
Deck covers have traditionally been made of sheet steel. Although metal deck covers are generally adequate, as a class they possess several disadvantages. First and foremost, such covers are obviously quite heavy. Also, metal deck covers tend to rattle, thereby creating unnecessary noise, particularly when the mower is traveling at high speeds across rough terrain. Steel covers are typically painted and tend to become scratched with use, particularly since they are located immediately atop the deck in an exposed area. Moreover, if a steel cover becomes dented, twisted or bent for one reason or another, this tends to misalign the holes in the cover relative to the mating studs, etc. attached to the deck, thereby making it very difficult to connect the cover to the deck.
Metal deck covers have historically been secured using conventional threaded fasteners, e.g., thumb screws or the like. While such fasteners hold deck covers in place fairly well, once they are removed during maintenance or repair procedures they are oftentimes misplaced. Also, threaded connectors, unless somehow locked in place, tend to loosen during use, contributing to the looseness and rattling of the metal deck covers.
One suggested approach to the deck cover fastener problem is to use overcenter clamps. Such clamps don't have a tendency to loosen like threaded connectors and are not subject to being lost during cleaning and servicing operations. However, they are comparatively costly; tend to be "knuckle busters"; and involve moving parts which can clog and corrode in the rugged operating environment of a commercial lawn mower.
With regard to the disadvantages associated with a metal deck cover, Ransomes Manufacturing Company has used plastic deck covers on its M48 series mowers, for example. While the Ransomes plastic deck covers address the noise problem associated with steel covers; are more scratch resistant than steel covers; are at least potentially lighter than steel covers; and are less likely to irreparably bend, twist or dent, Ransomes uses large threaded plastic knobs and Velcro strips to secure the M48 cover to the deck. The threaded knobs can loosen with use and easily be misplaced, as discussed above; and the use of Velcro strips to connect a deck cover to a deck can create problems, given the oil and debris which are normally present in the typical mowing environment.
The present invention addresses the problems associated with traditional metal cutting unit covers, and in particular the problems associated with metal covers and traditional threaded fastener means for securing such covers to mowing decks, for example.